1. Field of the Invention
The invention relates to a radiating apparatus, particularly an infrared radiating apparatus, having at least one radiation source which is broad in the direction transverse to the emission direction of interest.
2. Description of the Related Art
The radiating apparatus disclosed in Ger. AS 17 73 336 is an Infrared (IR) radiator for use in an IR analysis apparatus. In that apparatus, a layer of resistance material is fused onto an electrically non-conducting support which is resistant to high temperatures. The support is usually a plate of argillaceous earth material, such as clay. That is, the resistance material may comprise a solidified binder and a finely distributed electrically conducting material which is dispersed in the binder in an electrically conducting proportion. The binder preferably consists of a ceramic composition, whereas the electrically conducting material is a metal.
(PCT Application) WO 92/05411 describes an IR radiation source in the form of an electrically conducting metal strip placed under tension by a tension element. The strip carries a current.
The above apparatuses are relatively costly. It is necessary to furnish the main (substrate) body of the radiation source with a coating. Moreover, the suspension of the metal strip must employ spring-loaded means in order to ensure mechanical stability over the entire temperature range of the radiating apparatus. The spring loading entails a relatively high expense, both as to the structural elements and as to their assembly.
A radiating apparatus of the above-described type is essentially limited to a low power range because heat removal takes place via the tensioning elements. Overheating results if the power is increased to an appreciably higher level with consequent potential damage to the functioning of the radiating apparatus.
Further, the above arrangements tend to suffer fatigue in the face of stresses resulting from temperature changes, thereby decreasing the service life of the radiating apparatus.